Buggy code:
public abstract class StrMatcher { private static final StrMatcher COMMA_MATCHER = new StrMatcher . CharMatcher ( ',' ) ; private static final StrMatcher TAB_MATCHER = new StrMatcher . CharMatcher ( '\t' ) ; private static final StrMatcher SPACE_MATCHER = new StrMatcher . CharMatcher ( '<seq2seq4repair_space>' ) ; private static final StrMatcher SPLIT_MATCHER = new StrMatcher . CharSetMatcher ( "<seq2seq4repair_space>\t\n\r\f" . toCharArray ( ) ) ; private static final StrMatcher TRIM_MATCHER = new StrMatcher . TrimMatcher ( ) ; private static final StrMatcher SINGLE_QUOTE_MATCHER = new StrMatcher . CharMatcher ( '\'' ) ; private static final StrMatcher DOUBLE_QUOTE_MATCHER = new StrMatcher . CharMatcher ( '"' ) ; private static final StrMatcher QUOTE_MATCHER = new StrMatcher . CharSetMatcher ( "\'\"" . toCharArray ( ) ) ; private static final StrMatcher NONE_MATCHER = new StrMatcher . NoMatcher ( ) ; public static StrMatcher commaMatcher ( ) { } public static StrMatcher tabMatcher ( ) { } public static StrMatcher spaceMatcher ( ) { } public static StrMatcher splitMatcher ( ) { } public static StrMatcher trimMatcher ( ) { } public static StrMatcher singleQuoteMatcher ( ) { } public static StrMatcher doubleQuoteMatcher ( ) { } public static StrMatcher quoteMatcher ( ) { } public static StrMatcher noneMatcher ( ) { } public static StrMatcher charMatcher ( final char ch ) { } public static StrMatcher charSetMatcher ( final char ... chars ) { } public static StrMatcher charSetMatcher ( final String chars ) { } public static StrMatcher stringMatcher ( final String str ) { } protected StrMatcher ( ) { } public abstract int isMatch ( char [ ] buffer , int pos , int bufferStart , int bufferEnd ) ; public int isMatch ( final char [ ] buffer , final int pos ) { } static final class CharSetMatcher extends StrMatcher { private final char [ ] chars ; CharSetMatcher ( final char [ ] chars ) { } @ Override public int isMatch ( final char [ ] buffer , final int pos , final int bufferStart , final int bufferEnd ) { return ( Arrays . binarySearch ( chars , buffer [ pos ] ) ) >= 0 ? 1 : 0 ; } } static final class CharMatcher extends StrMatcher { private final char ch ; CharMatcher ( final char ch ) { } @ Override public int isMatch ( final char [ ] buffer , final int pos , final int bufferStart , final int bufferEnd ) { return ( ch ) == ( buffer [ pos ] ) ? 1 : 0 ; } } static final class StringMatcher extends StrMatcher { private final char [ ] chars ; StringMatcher ( final String str ) { } @ Override public int isMatch ( final char [ ] buffer , int pos , final int bufferStart , final int bufferEnd ) { <START_BUG> int len = chars . length ; <END_BUG> if ( ( pos + len ) > bufferEnd ) { return 0 ; } for ( int i = 0 ; i < ( chars . length ) ; i ++ , pos ++ ) { if ( ( chars [ i ] ) != ( buffer [ pos ] ) ) { return 0 ; } } return len ; } } static final class NoMatcher extends StrMatcher { NoMatcher ( ) { } @ Override public int isMatch ( final char [ ] buffer , final int pos , final int bufferStart , final int bufferEnd ) { return 0 ; } } static final class TrimMatcher extends StrMatcher { TrimMatcher ( ) { } @ Override public int isMatch ( final char [ ] buffer , final int pos , final int bufferStart , final int bufferEnd ) { return ( buffer [ pos ] ) <= 32 ? 1 : 0 ; } } }

Fix:
final int len = chars . length ;